My opinion is that it all stems from human curiosity - an evolutionary trait that has led to our extended survival as a species, our technology, and our society. Compared to other species, we retain more of our child-like curiosity (and playfulness) as we mature. Tied to this curiosity, we also have a psychological need for closure...i.e. "an answer" to the question in front of us. Unknowns leave an emotional void in all of us. People have different levels of a need for closure of that void and some are willing to accept lesser degrees of verified "truths" in order to obtain that emotional satisfaction in that closure. This then becomes a belief that may be completely irrational but has satisfied the emotional need.